In the prior art, plug connectors are known which are fitted to the ends of cables in such a way that the strands of a cable are connected in the interior of a plug connector with the contacts of this plug connector. The contacts are retained in a base element of the plug connector. The base element is protected in an armoured box which is itself surrounded by at least one lower cover and one upper cover. In general terms, these plug connectors exhibit centring feet elements on their front face which is intended to come in contact with the complementary device. These centring feet elements allow for the alignment to be improved between the contacts of the plug connector and those of the complementary device. In this way mutual wear and damage can be avoided during connection and disconnection operations. These centring feet elements are protruding, and are inserted into recesses in the complementary device.
In order to retain the plug connector on the device, retention means are known such as screws, which can, for example, interact with the covers and, on the other hand, also with receptacles located on the complementary device. These means present the disadvantage of being unwieldy in their dimensions.
From the teaching of the document FR-A-2,806,218 a type of plug connector is known which is characterised by the fact that these means of retention are located at the level of the centring feet elements. With such a solution the dimensional encumbrance caused by these retention means is minimised. To this end, the centring feet elements each comprise a slot from which a retention means passes. For example, means of retention are used which comprise elastic tongue elements, each provided with a lug serving as a locking piece when interacting with an offset piece on the complementary device. The lug of the tongue passes from the slot at the level of an upper face of the centring foot element.
In order to provide sufficient tear resistance for this elastic tongue, it is cut for preference from a metallic sheet of a certain thickness. The cutting is designed to create a fine tongue with lateral broadening, in order to form the locking arrangement This tongue is of one piece with a wide leg piece, which allows for the cut-off piece to be retained in the base. The tongue and the leg piece are connected to one another so as to form feet elements in a U-shape. This cut-off piece is inserted vertically into a centring foot element of the lower cover, in such a way as to exhibit on the outside of the slot a sharp edge formed by the thickness of the cutoff piece. After insertion, the feet of this U shape are parallel to the upper face of the centring foot element. Accordingly, the lateral broadening, the locking arrangement, emerges orthogonally to the upper face of the centring foot element.
To complete the assembly of such a plug connector, the upper cover is closed into the lower cover in such a way as to allow for the passage of the centring feet elements and their elastic locking arrangement from the front face. Due to this, the lower and upper covers have distinctly different shapes.
When a plug connector assembled in this way is connected to a complementary device, the broadened area forming the locking arrangement is retained by a border of a cavity into which the centring foot element is inserted. When a pull is exerted on the cable fitted in this plug connector, the tractive force is transferred to the covers, because they are crimped around the cable. Because the locking means are retained in the cover, this transfers the traction force by means of the locking arrangement, which has this traction force applied at the point of contact between the broadening part and the border of the cavity. This traction incurs a rotational movement of the locking means in the shape of a U. This rotation is effected with the point of contact as the centre of rotation. Under the effect of this traction, the hollow of the U opens into the interior of the covers.
In order to avoid this rotational movement and the deformation of the locking means under the strain, provision is made for the reinforcing of the retention leg. The reinforcing of this leg, however, poses a problem of dimensional encumbrance and weight overload of the plug connector thus obtained. Nevertheless, without such reinforcement it will not be possible to achieve sufficient resistant to tearing.
In parallel with this, in order to increase the rigidity of the centring foot element, which contains a slot, provision is made for the insertion of a bracing element around the locking tongue. This bracing element is likewise inserted from the upper face of the lower cover, and has a U-shaped cross-section. It is inserted in front of the locking means, and it is the locking means which ensure the retention of this bracing element in the cover.
The known plug connectors pose a problem. In effect, even if the structure of the chosen locking means allows for their spatial dimensions to be reduced, particularly by reducing the width of those plug connectors which do not necessarily have to exhibit locking means on their peripheries, the complexity of the layout is increased. In effect, the means of locking used are heavier, and present greater encumbrance in the limited space of the slot of the centring foot element. In addition, such a structure requires the locking means to be located in the cover, which in turn requires the lower and upper covers to be different from one another. The number of components necessary to constitute such a plug connector is also increased.
Moreover, when this type of plug connector, connected to a complementary device, is subjected to a tearing force, the locking means are deformed inside the plug connector, to the point of almost coming free from the slot, and causing the lower and upper covers to come apart from one another.
The problem of the invention is to rectify the problems referred to by proposing a plug connector provided with locking means directly located in the interior of the base of the plug connector, with the base itself exhibiting centring feet elements which, moreover, enhance the precision of the fitting of the connector on a complementary device. For preference, these means are inserted from a front face of the base element, as are the contacts of the plug connector, which are likewise mounted on the base projecting from its rear face. In addition, with this solution provision can be made for identical cover pieces to surround the lower and upper faces of the base element.
In order to guarantee that the locking means are maintained in the interior of the base element when subjected to the insertion or withdrawal forces of the plug connector in relation to the complementary device, the locking means comprise two piercing means in addition to the elastic tongue provided with its locking arrangement. These two piercing means are divided between both sides of the tongue; i.e. the tongue is simultaneously connected to the first piercing means, and to the second piercing means. The first piercing means is not directly connected to the second piercing means.
These piercing means are intended to be inserted into independent cavities in the cavity in which the tongue is located. For preference, these piercing means and the tongue each have an elongated shape in such a manner that they are parallel. Three cavities are formed in the base element, and there are accordingly three cavities parallel to one another, into which the three “parallel branches” of the locking means can be introduced. The two piercing means interact respectively with the walls of the base of the two different cavities, while the elastic tongue can freely pass beyond the confines of its cavity, towards the outside of the centring foot element, with one end exhibiting a stump serving as a locking element in order to interact with the edge of the complementary device.